Saw chain

ABSTRACT

A cutter tooth for a saw chain having a reappearing sequence of pivotally connected center and side links wherein the cutter tooth is made up of two separate and flexible center mounted cutter tooth elements which extend laterally and upwardly from the center line of the chain to form the cutter tooth. The cutter tooth elements are made of flexible steel and are of proper thickness to allow the cutter elements to flex outwardly under cutting loads to obtain a kerf which is slightly wider than the mechanical width of the cutter elements when not under load. The two piece cutter tooth has its own depth gauge integral therewith for positive control. A pair of novel L-shaped raker teeth is used in combination with the two piece cutter. Each raker tooth is flat in a transverse direction, has a reverse angle on its leading edge as compared to conventional rakers. The raker teeth are oppositely directed and so constructed as to remove chips across the complete width of the kerf to clear the way for succeeding depth gauge elements. Each raker tooth also has its own integral depth gauge.

United States Patent 1 Lemery [111 3,745,870 [451 July 17,1973

[21] App]. No.: 166,033

[52] US. Cl. 83/833 [51] Int. Cl B27b 33/14 [58] Field of Search 143/135R, 135 G,

[56] References Cited UNITED STATES PATENTS 3,346,025 10/1967 Andersonet al...: 143/135 R 2,762,227 9/1956 Tweedie 143/135 R FOREIGN PATENTSOR APPLICATIONS 152,505 11/1955 Sweden 143/135 R Primary Examiner-DonaldR. Schran Attorney-Richard W. Seed et a].

[57] ABSTRACT A cutter tooth for a saw chain having a reappearingsequence of pivotally connected center and side links wherein the cuttertooth is made up of two separate and flexible center mounted cuttertooth elements which extend laterally and upwardly from the center lineof the chain to form the cutter tooth. The cutter tooth elements aremade of flexible steel and are of proper thickness to allow the cutterelements to flex outwardly under cutting loads to obtain a kerf which isslightly wider than the mechanical width of the cutter elements when notunder load. The two piece cutter tooth has its own depth gauge integraltherewith for positive control. A pair of novel L-shaped raker teeth isused in combination with the two piece cutter. Each raker tooth is flatin a transverse direction, has a reverse angle on its leading edge ascompared to conventional rakers. The raker teeth are oppositely directedand so constructed as to remove chips across the complete width of thekerf to clear the way for succeeding depth gauge elements. Each rakertooth also has its own integral depth gauge.

17 Claims, 5 Drawing Figures INVENTOR. DOUGLAS J1. LEMERY ATTORNEYS SAWCHAIN This invention relates to saw chains for use on portable orstationary chainsaws and more particularly to a new and improved sawchain construction including novel cutter and raker tooth structures.The cutter tooth construction of the present invention provides abifurcated or U-tooth cutter link with an integral depth gauge whereinthe cutter elements are capable of lateral flexing under cutting loads.The novel raker tooth provides for more complete chip and fiber removalas a result of its novel cooperation with the cutter tooth.

Although many configurations of cutter tooth and raker toothcombinations have been used in the prior art and in particular U orV-shaped bifurcated and center-mounted cutter teeth, the problems ofbinding, overheating and excessive power requirements have not beensolved. These factors result in very slow cutting and hence thebifurcated center-mounted cutter tooth has not been competitive comparedto conventional designs. In addition, the problems encountered inmanufacturing the conventional U or V tooth render the cost prohibitiveand the reliability of the tooth poor. For instance, as many as 17forming steps including three annealings may be necessary in itsformation. Because the metal must be split and upset, close tolerancescannot be held eg. width, thickness of the tooth sides, etc., and theresulting tooth breaks or bends very easily, even under normal runningconditions, because of the manner in which it must be formed. Anotherdrawback which adds to the expense of such teeth is the sophisticatedequipment needed for its manufacture, including expensive short lifedies. The present invention seeks to eliminate these problems byproviding a birfurcated cutter tooth which can be easily formed and isinexpensive to manufacture in quantity. Only conventional andinexpensive dies are necessary for its formation and tolerances may beclosely held. Since the metal need only be bent with reasonable radiiand the metal remains flexible, breakage is held to an absolute minimum.The cutter elements are permitted to flex laterally in both directionsunder cutting loads and hence the initial shock of any binding actionwill be relieved by inward flexing of the elements. The ability of thecutter elements making up the cutter tooth to deflect laterallyoutwardly under cutting loads, such that the distance between the cutterelements is actually increased beyond the mechanical width of the tooth,provides a more free-running and non-binding saw chain whichconsequently runs cooler and requires less power.

The primary object of the present invention is therefore to provide abifurcated cutter tooth construction and a cutter, raker and depth gaugesequence which results in far superior performance of the chain in termsof eliminating binding, overheating, excessive power requirements,provision for better chip removal and speed of cutting.

Another and more specific object of the present invention is to providea bifurcated center-mounted cut ter tooth construction wherein thecutter elements making up the tooth are of the proper thickness andconfiguration so as to be flexible, allowing the cutter elements to flexlaterally in both directions to increase the width of the kerf and avoidshock loading during operation.

BRIEFDESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view of asection of saw chain embodying the invention;

FIG. 2 is a top plan view thereof;

FIG. 3 is an elevational view of a single cutter tooth;

FIG. 4 is a front elevational view of the bifurcated cutter toothillustrating the flexibility of the cutter elements; and

FIG. 5 is a front elevational view of the raker tooth.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring in detail to thedrawings, FIGS. 1 and 2 illustrate a sequence of links designated in itsentirety by the numeral 10 and it will be understood that such sequenceis repeated in the same order and arrangement throughout the length ofthe chain. The particular chain described by way of example in thepresent specification will be understood to be a inch pitch chain withall sizes and dimensions referred to being related thereto. The sequenceincludes side links, spacer drive links and drive links which mount thecutter teeth and raker teeth along with their depth gauges integraltherewith. The side links 11 along with the rivets 12 serve to join thecenter links in end-to-end pivotal relationship in a well-known mannerwith the bottom surfaces 13 and 14 of the side links providing a surfacefor supporting the chain on the rails of a saw bar, not shown. The sidelinks 11 are merely positioned on opposite sides of the chain and areidentical and interchangeable.

The center links of the chain are of three different forms, spacerlinks, raker links and cutter links. The links 16 are identical andconstitute the spacer links which include sprocket engaging portions 17which engage and are trained about the drive sprocket of the engine orpower unit (not shown) for driving the chain. The configuration of thespacer links are of a design well known to those skilled in the art. Theconfiguration of the root portions of all of the center links may beidentical and of a standard configuration which needs no furtherexplanation.

The novel cutter link of the present invention is indicated at 26 andcomprises two pieces 26a and 26b which are in effect mirror images ofone another. Each piece 260 and 26b is formed with a sprocket engagingroot portion substantially identical to the sprocket engaging portionsof the other center links previously described. When the chain isassembled as illustrated in FIG. 1, the two halves are held together andwill be approximately equal the thickness of the remaining center links.It would of course be possible to permanently join the link pieces oruse an integral structure so long as flexibility of the two halves ismaintained. Each of the cutter link pieces has integrally formed thereona depth gauge portion 27 and a side cutter element 28. The side cutterelements extend laterally from the central body portion of the linkhalves and have an approximate 0.05 inch radius at 29 and at 31 with theupper tips of the wing portion or cutter element being disposed at anapproximate 7 angle with the vertical. The cutting edges 32 are flat andmay be in the order of 0.015 to 0.020 of an inch in width. As seen mostclearly in FIG. 3, a longitudinal rake angle of approximately 10 isgiven to the cutter elements 28 with this angle being variable asdesired. The depth gauge portion 27 will, of course, be slightly less inheight than the forward cutting faces of the members 28. It isrecommended that this difference be maintained in the order of 0.035inches. When not under cutting load, the distance between the outsideedges of the wing portion should be in the neighborhood of 0.315 to0.320-

inches. The leading or cutting faces of the elements 28 may be eitherstraight or curved to allow for easy filing in the field.

As previously mentioned, each half of the cutter tooth is fabricatedfrom a relatively thin piece of sheet metal which will be in theneighborhood of 0.029 inches thick or approximately one half drive linkthickness. The steel used to fabricate the tooth half must be flexiblesuch that the lateral wings or cutter elements 28 are free to flexindependently when placed under cutting loads. Because of the side rakeor taper of approximately 4-% the tendency will be for the wings to flexoutwardly causing the scores or kerfs cut by the cutter elements to bespaced further apart than the mechanical width of the tooth. Thisincrease in width will be in the neighborhood of 0.012 inches with arange of 0.006 to 0.012 inches. In practice, -45 steel, as well asregular steel, has been used and it is contemplated that regular chainsaw steel would be suitable and perhaps improved if alloyed with nickelto provide elasticity.

The center links 18 and 19 include integral L-shaped raker elements 21and 22 respectively as well as depth gauge elements 23 and 24, alsointegral with the links. The depth gauge elements 23 and 24 are, ofcourse, spaced at a predetermined distance ahead of the raker teeth andfunction to remove the material between the scores made by the cutterelements 28. It will also be noted, referring to FIG. 2, that the rakerteeth 21 and 22 extend laterally in opposite directions from the centerline of the chain with each raker element being approximately 0.020inches inside the width of the U- cutter tooth. The top surface of theraker elements 21 and 22 may be formed with a slight longitudinal rakeangle of 4.5 as illustrated in FIG. 2 in the same manner as the cutterelement. This angle may, of course, be modified without departing fromthe spirit of the invention. It will also be noted that the top surfaceis downwardly inclined toward the trailing end of the link with theangle of inclination being approximately 10 as in the case of the cuttertooth which also may be varied depending upon the type of wood, thespeed of the chain and other varyable factors. The height of the depthgauge elements 23 and 24 may be determined so as to give the desiredcutting characteristics, but preferably should be 0.035 inches below thecutter tooth or the same height as the cutter tooth. In this connectionthe height of the raker should preferably be from 0.010 to 0.015 inchesbelow rhe cutter tooth.

As may be seen most clearly in FIG. 5, the raker tooth rises verticallyout of the center line of the chain and then is directed laterally toone side or the other with a radius 33 between the vertical and lateralportion. This formation results in an L-shaped crosssection with the topsurface of the raker being flat, i.e. having no transverse angle. Thereason for the flat top surface is to avoid cutting across fibers whichhave been already severed by the U-tooth cutters. As previsouslymentioned, each raker tooth has its own depth integral gauge in order toprevent what is known as wild cutting" which results from separating theraker and its depth gauge. With the integral depth gauge, absolutecontrol of the depth of cut of the raker is obtained even when boringsince the depth of cut remains constant, the chain runs smoother and ishence easier to handle so that the user does not have to fight the cahineven under the most adverse conditions. In this connection, it will benoted that the radius of the L- shaped raker tooth goes beyond thecenter line of the chain which has the result of insuring that thefollowing depth gauges will ride on a constant and flat surface on thebottom of the kerf being cut. This also tends to produce a smoothcutting action.

As seen in FIG. 5, the outboard edges of the raker teeth are not coinedbut retain their full thickness as illustrated at 34. The purpose ofthis formation of the raker tooth is to sever any remaining fiber hairswhich may remain from the scoring done by the cutter elements. Thisinsures a full width kerf and prevents binding and clogging.

Because of the flat top surface of the raker element, it is satisfactoryto file the leading edge of the raker element straight across, as isconventional, without causing a pile-up or clogging of chips as thechain moves. It is preferable, however, to file the leading edges of theraker elements in a direction reverse from that of conventional rakerelements such as shown in FIG. 2. The top surface of the raker toothwill thus have a rake angle which is inclined away from the direction ofmovement of the chain and which is defined for the purpose of thisspecification as a positive rake angle. This angle is preferably in theneighborhood of from 10 to 20. This formation gives the raker tooth thetendency to lead into the cut made by the cutter elements thus insuringa complete removal of the chip between the two cuts or scores made bythe cutter element. Also, the result of this formation is to insure thatall hair-like fibers are severed in order to prevent binding.

From the foregoing it will be apparent that the present inventionprovides novel, useful and unobvious results in'cutter tooth and rakertooth construction as well as link sequence for saw chains of thecharacter under consideration. While the prefered form of the inventionhas been illustrated and described, it is understood that it is capableof modification and addition without departing from the principlethereof. Accordingly, the invention is not to be limited to the exactform illustrated but only by the literal interpretation of the claimsdepended hereto.

The embodiments of the invention in which a particular property orprivilege is claimed are defined as follows:

1. A saw chain comprising; a plurality of pivotally joined links, saidlinks being assembled in link sequences and each sequence including aplurality of center links pivotally connected by side links, said centerlinks including body portions with sprocket engaging root portionsextending therefrom, some of said center links including a raker toothextending from the body portion in a direction opposite to the rootportion, and at least one of said center links including a bifurcatedcutter tooth presenting spaced side cutter elements, said cutter toothextending from the body portion in a direction opposite said rootportion, said cutter tooth center link being a composite of two separatemirror image link elements, each of said link elements having its ownroot portion, body portion and side cutter element, said cutter linkelements being made from relatively thin flexible metal so as to allowflexing and deformation under normal cutting loads in the area betweenthe cutter elements and the body portions and being so disposed as tocause flexing laterally outwardly during cutting to increase thedistance therebetween beyond the mechanical width of the tooth, anddepth guage means associated with said raker and cutter tooth to controlthe depth of cut thereof.

2. The saw chain according to claim 1 wherein; each sequence includes atleast two raker links and a cutter link therebetween, said raker teethhaving oppositely directed laterally extending raker elements, thecombined width of said raker elements being less than the mechanicalwidth of the cutter tooth.

3. The saw chain according to claim 2 including; at least one spacercenter link between each of said raker links and the cutter link.

4. The combination according to claim 3 wherein; said depth guage meanscomprises; a depth guage element integral with each said links.

5. The combination according to claim 4 wherein the thickness of saidcutter link elements is approximately one half the thickness of theremaining center mounted links.

6. The combination according to claim 5 wherein said cutter tooth isU-shaped in cross-section.

7. A saw chain comprising a plurality of pivotally joined links, saidlinks being assembled in link sequences and each sequence including aplurality of center links pivotally connected by side links, said centerlinks including body portions with sprocket engaging root portionsextending therefrom, some of said center links including a raker toothextending from the body portion in a direction opposite to the rootportion, and at least one of said center links including a bifurcatedcutter tooth presenting spaced mirror image side cutter elements, saidcutter tooth extending from the body portion in a direction oppositesaid root portion, said cutter elements being made from flexible metalso as to allow flexing and deformation under normal cutting loads in thearea between the cutter elements and the associated body portion andbeing so disposed as to cause flexing laterally outwardly during cuttingto increase the distance therebetween beyond the mechanical width of thetooth, and depth guage means associated with said raker and cutter toothto control the depth of cut thereof.

8. The saw chain according to claim 7 wherein, each sequence includes atleast two raker links and a cutter link therebetween, said raker teethhaving oppositely directed laterally extending raker elements, thecombined width of said raker elements being less than the mechanicalwidth of the cutter tooth.

9. The saw chain according to claim 8 wherein; each raker tooth isL-shaped in cross-section having a vertical portion extending in theopposite direction from the associated root portion and a flat topportion extending laterally at right angles to the vertical portion witha radius therebetween, said depth guage means associated with the rakertooth being integral therewith and located on the centerline of thechain, said radius being located on the opposite side of said depthguage from said flat top portion, whereby the flat top portion of theraker will remove a wood chip of at least sufficient width to clear thekerf for succeeding depth guages.

10. The saw chain according to claim 9 wherein the leading edge of saidraker tooth has a positive rake angle in the direction of travel of saidchain.

11. For use in a saw chain, a center-link-mounted cutter toothcomprising; first and second link elements, said link elements beingmirror images of one another and each including a body portion, asprocket engaging root portion and a cutter element extending laterallyoutwardly in a direction opposite from said root portion, said linkelements being made from relative flexible metal so as to allow flexingand deformation under normal cutting loads in the area between thecutter elements and the body portion, said cutter elements being sodisposed as to cause flexing laterally outwardly during cutting toincrease the distance therebetween beyond the mechanical width of thetooth.

12. The cutter tooth according to claim 11 including; depth guageelementsintegral with the body portion of each said link elements spacedahead of the cutter elements in the direction of travel of the chain.

13. The combination according to claim 1] wherein; the thickness of saidcutter link elements is approximately one half the thickness of theremaining center mounted links of the saw chain.

14. The combination according to claim 12 wherein; the thickness of saidcutter link elements is approximately one half the thickness of theremaining center mounted links of the saw chain.

15. The cutter tooth according to claim 14 wherein; said cutter tooth isU-shaped in cross-section.

16. For use in a saw chain, a center-link-mounted cutter toothcomprising; a body portion with sprocket engaging root portionsextending therefrom, and spaced mirror image side cutter elementsextending from the body portion in a direction opposite the root portionand laterally thereof, said cutter elements being made from flexiblemetal so as to allow flexing and deformation under normal cutting loadsin the area between the cutter elements and the associated body portionand being so disposed as to cause flexing laterally outwardly duringcutting to increase the distance therebetween beyond the mechanicalwidth of the tooth.

17. The cutter tooth according to claim 16 including; depth guageelements integral witllt the body portion of each said cutter elementsspaced ahead of the cutter elements in the direction of travel of thechain.

' a a: t a a:

1. A saw chain comprising; a plurality of pivotally joined links, saidlinks being assembled in link sequences and each sequence including aplurality of center links pivotally connected by side links, said centerlinks including body portions with sprocket engaging root portionsextending therefrom, some of said center links including a raker toothextending from the body portion in a direction opposite to the rootportion, and at least one of said center links including a bifurcatedcutter tooth presenting spaced side cutter elements, said cutter toothextending from the body portion in a direction opposite said rootportion, said cutter tooth center link being a composite of two separatemirror image link elements, each of said link elements having its ownroot portion, body portion and side cutter element, said cutter linkelements being made from relatively thin flexible metal so as to allowflexing and deformation under normal cutting loads in the area betweenthe cutter elements and the body portions and being so disposed as tocause flexing laterally outwardly during cutting to increase thedistance therebetween beyond the mechanical width of the tooth, anddepth guage means associated with said raker and cutter tooth to controlthe depth of cut thereof.
 2. The saw chain according to claim 1 wherein;each sequence includes at least tWo raker links and a cutter linktherebetween, said raker teeth having oppositely directed laterallyextending raker elements, the combined width of said raker elementsbeing less than the mechanical width of the cutter tooth.
 3. The sawchain according to claim 2 including; at least one spacer center linkbetween each of said raker links and the cutter link.
 4. The combinationaccording to claim 3 wherein; said depth guage means comprises; a depthguage element integral with each said links.
 5. The combinationaccording to claim 4 wherein the thickness of said cutter link elementsis approximately one half the thickness of the remaining center mountedlinks.
 6. The combination according to claim 5 wherein said cutter toothis U-shaped in cross-section.
 7. A saw chain comprising a plurality ofpivotally joined links, said links being assembled in link sequences andeach sequence including a plurality of center links pivotally connectedby side links, said center links including body portions with sprocketengaging root portions extending therefrom, some of said center linksincluding a raker tooth extending from the body portion in a directionopposite to the root portion, and at least one of said center linksincluding a bifurcated cutter tooth presenting spaced mirror image sidecutter elements, said cutter tooth extending from the body portion in adirection opposite said root portion, said cutter elements being madefrom flexible metal so as to allow flexing and deformation under normalcutting loads in the area between the cutter elements and the associatedbody portion and being so disposed as to cause flexing laterallyoutwardly during cutting to increase the distance therebetween beyondthe mechanical width of the tooth, and depth guage means associated withsaid raker and cutter tooth to control the depth of cut thereof.
 8. Thesaw chain according to claim 7 wherein, each sequence includes at leasttwo raker links and a cutter link therebetween, said raker teeth havingoppositely directed laterally extending raker elements, the combinedwidth of said raker elements being less than the mechanical width of thecutter tooth.
 9. The saw chain according to claim 8 wherein; each rakertooth is L-shaped in cross-section having a vertical portion extendingin the opposite direction from the associated root portion and a flattop portion extending laterally at right angles to the vertical portionwith a radius therebetween, said depth guage means associated with theraker tooth being integral therewith and located on the centerline ofthe chain, said radius being located on the opposite side of said depthguage from said flat top portion, whereby the flat top portion of theraker will remove a wood chip of at least sufficient width to clear thekerf for succeeding depth guages.
 10. The saw chain according to claim 9wherein the leading edge of said raker tooth has a positive rake anglein the direction of travel of said chain.
 11. For use in a saw chain, acenter-link-mounted cutter tooth comprising; first and second linkelements, said link elements being mirror images of one another and eachincluding a body portion, a sprocket engaging root portion and a cutterelement extending laterally outwardly in a direction opposite from saidroot portion, said link elements being made from relative flexible metalso as to allow flexing and deformation under normal cutting loads in thearea between the cutter elements and the body portion, said cutterelements being so disposed as to cause flexing laterally outwardlyduring cutting to increase the distance therebetween beyond themechanical width of the tooth.
 12. The cutter tooth according to claim11 including; depth guage elements integral with the body portion ofeach said link elements spaced ahead of the cutter elements in thedirection of travel of the chain.
 13. The combination according to claim11 wherein; the thickness of said cutter link elements is approximatelyone half the thickness of thE remaining center mounted links of the sawchain.
 14. The combination according to claim 12 wherein; the thicknessof said cutter link elements is approximately one half the thickness ofthe remaining center mounted links of the saw chain.
 15. The cuttertooth according to claim 14 wherein; said cutter tooth is U-shaped incross-section.
 16. For use in a saw chain, a center-link-mounted cuttertooth comprising; a body portion with sprocket engaging root portionsextending therefrom, and spaced mirror image side cutter elementsextending from the body portion in a direction opposite the root portionand laterally thereof, said cutter elements being made from flexiblemetal so as to allow flexing and deformation under normal cutting loadsin the area between the cutter elements and the associated body portionand being so disposed as to cause flexing laterally outwardly duringcutting to increase the distance therebetween beyond the mechanicalwidth of the tooth.
 17. The cutter tooth according to claim 16including; depth guage elements integral with the body portion of eachsaid cutter elements spaced ahead of the cutter elements in thedirection of travel of the chain.